Support arm for desk lamp



FIG. 1 is a perspective view thereof;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side view, the left side view being a mirror image;

FIG. 4 is a back view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines shown in the drawing are environmental only and form no part of the claimed design. 

The ornamental design for support arm for desk lamp, as shown and described. 